Method of making alcohols

ABSTRACT

Methods and systems for the synthesis of alcohol are described herein. The methods and systems incorporate the novel use of a high shear device to promote dispersion and solubility of olefins in water. The high shear device may allow for lower reaction temperatures and pressures and may also reduce reaction time. In an embodiment, a method of making an alcohol comprises introducing an olefin into a water stream to form a gas-liquid stream. The method further comprises flowing the gas-liquid stream through a high shear device so as to form a dispersion with gas bubbles having a mean diameter less than about 1 micron. In addition, the method comprises contacting the gas-liquid stream with a catalyst in a reactor to hydrate the olefin gas and form an alcohol.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 60/946,499 and U.S. ProvisionalPatent Application No. 60/946,465, filed Jun. 27, 2007, the disclosuresof which are hereby incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

TECHNICAL FIELD

This invention relates generally to the field of chemical reactions.More specifically, the invention relates to methods of synthesizingalcohols incorporating high shear.

BACKGROUND OF THE INVENTION

A process for hydrating an olefin, especially a lower olefin such asethylene, propylene or butene, to prepare a corresponding alcohol suchas ethanol, propanol or butanol, is industrially important as alcoholhas applications in many areas of industry, science, medicine, andtechnology. In light of the recent developments in using ethanol as afuel source, improved processes for producing alcohol has become evenmore desirable Various processes are known for the alcohol hydrationreaction, but using a mineral acid such as sulfuric acid or phosphoricacid as a catalyst has been the most prevalent industrial method ofproduction. In addition, isopropanol (isopropyl alcohol) is widely usedtoday as a solvent, disinfectant and fuel additive. In the chemicalindustry it is a very useful intermediate in organic synthesis.

Typically, alcohols such as ethanol or isopropanol may be produced byhydrating olefins using a phosphoric acid supported on a silica gel. Inthis process, however, phosphoric acid supported on the silica gel maybe eluted causing degradation of catalyst activity. Accordingly, it isnecessary to perpetually add phosphoric acid. Therefore, problems arisein connection with the treatment of the discharged waste liquid and thecorrosion of the material of equipment. Furthermore, a large quantity ofenergy is necessary for recovery of unreacted ethylene or separation andpurification of the produced ethanol because the conversion of ethyleneis low.

A liquid phase process using sulfuric acid has also been widely adoptedfor the hydration of propylene or butenes, industrially. However, inthis process, a large quantity of energy is necessary for hydrolysis ofa sulfuric acid ester once formed. Because of the concentration andregeneration of the diluted aqueous sulfuric acid solution, equipmentmay be violently corroded by the acid at high temperatures.

From equilibrium considerations, it is preferred that the hydration ofolefins be carried out at a low temperature under a high pressure, andordinarily, these reaction conditions provide high conversions ofolefins to alcohols. However, it is necessary to obtain an industriallysatisfactory rate of reaction, and practically, severe conditions ofhigh temperatures and high pressures are adopted for obtaining such ahigh rate of reaction. For these reasons, it is desired to develop ahighly active solid acid catalyst for the hydration of olefins, which iscapable of reducing the consumption of energy and not causing corrosionof equipment or other trouble.

Attempts have been made to use solid catalysts for the hydration ofolefins. For example, processes have been proposed using complex oxidescomposed of silica, alumina, zirconia, titanium oxide, molybdenum oxideand tungsten oxide, metal phosphates such as aluminum phosphate andzirconium phosphate, and crystalline aluminosilicates called “zeolites”such as mordenite and Y type zeolite. However, these catalysts possess alow activity and the activity is gradually degraded when the reaction iscarried out at a high temperature.

As can be seen from the above discussion, previous methods rely onimproving the catalysts used in the hydration reaction. Presently,little or no investigation has been done in improving mixing of thereactants e.g. olefins and water for improving and optimizing thereaction.

Consequently, there is a need for accelerated methods for making analcohol by improving the mixing of olefins into the water phase.

BRIEF SUMMARY

Methods and systems for the synthesis of alcohol are described herein.The methods and systems incorporate the novel use of a high shear deviceto promote dispersion and solubility of olefins in water. The high sheardevice may allow for lower reaction temperatures and pressures and mayalso reduce reaction time. Further advantages and aspects of thedisclosed methods and system are described below.

In an embodiment, a method of making an alcohol comprises introducing anolefin into a water stream to form a gas-liquid stream. The methodfurther comprises flowing the gas-liquid stream through a high sheardevice so as to form a dispersion with gas bubbles having a meandiameter less than about 1 micron. In addition, the method comprisescontacting the gas-liquid stream with a catalyst in a reactor to hydratethe olefin gas and form an alcohol.

In an embodiment, a system for hydrating an olefin comprises at leastone high shear device comprising a rotor and a stator. The rotor and thestator are separated by a shear gap in the range of from about 0.02 mmto about 5 mm. The shear gap is a minimum distance between the rotor andthe stator. The high shear device is capable of producing a tip speed ofthe at least one rotor of greater than about 23 m/s (4,500 ft/min). Inaddition, the system comprises a pump configured for delivering a liquidstream comprising liquid phase to the high shear device. The system alsocomprises a reactor for hydrating an olefin coupled to the high sheardevice. The reactor is configured for receiving said dispersion fromsaid high shear device.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter that form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand the specific embodiments disclosed may be readily utilized as abasis for modifying or designing other structures for carrying out thesame purposes of the present invention. It should also be realized bythose skilled in the art that such equivalent constructions do notdepart from the spirit and scope of the invention as set forth in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process flow diagram of a process for the making alcohol,according to certain embodiments of the invention.

FIG. 2 is a longitudinal cross-section view of a multi-stage high sheardevice, as employed in an embodiment of the system of FIG. 1.

NOTATION AND NOMENCLATURE

Certain terms are used throughout the following description and claimsto refer to particular system components. This document does not intendto distinguish between components that differ in name but not function.

In the following discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to . . . ”.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The disclosed methods and systems for the hydration of olefins employ ahigh shear mechanical device to provide rapid contact and mixing of theolefin gas and water in a controlled environment in the reactor/mixerdevice. The term “olefin gas” as used herein includes both substantiallypure olefins as well as gaseous mixtures containing olefins. Inparticular, embodiments of the systems and methods may be used in theproduction of alcohols from the hydration of olefins. Preferably, themethod comprises a heterogeneous phase reaction of liquid water with anolefin gas. The high shear device reduces the mass transfer limitationson the reaction and thus increases the overall reaction rate.

Chemical reactions involving liquids, gases and solids rely on time,temperature, and pressure to define the rate of reactions. In caseswhere it is desirable to react two or more raw materials of differentphases (e.g. solid and liquid; liquid and gas; solid, liquid and gas),one of the limiting factors in controlling the rate of reaction involvesthe contact time of the reactants. In the case of heterogeneouslycatalyzed reactions there is the additional rate limiting factor ofhaving the reacted products removed from the surface of the catalyst toenable the catalyst to catalyze further reactants. Contact time for thereactants and/or catalyst is often controlled by mixing which providescontact with two or more reactants involved in a chemical reaction. Areactor assembly that comprises an external high shear device or mixeras described herein makes possible decreased mass transfer limitationsand thereby allows the reaction to more closely approach kineticlimitations. When reaction rates are accelerated, residence times may bedecreased, thereby increasing obtainable throughput. Product yield maybe increased as a result of the high shear system and process.Alternatively, if the product yield of an existing process isacceptable, decreasing the required residence time by incorporation ofsuitable high shear may allow for the use of lower temperatures and/orpressures than conventional processes.

System for Hydration Olefins. A high shear olefin hydration system willnow be described in relation to FIG. 1, which is a process flow diagramof an embodiment of a high shear system 100 for the production ofalcohols via the hydration of olefins. The basic components of arepresentative system include external high shear device (HSD) 140,vessel 110, and pump 105. As shown in FIG. 1, the high shear device maybe located external to vessel/reactor 110. Each of these components isfurther described in more detail below. Line 121 is connected to pump105 for introducing either an olefin reactant. Line 113 connects pump105 to HSD 140, and line 118 connects HSD 140 to vessel 110. Line 122 isconnected to line 113 for introducing an olefin gas. Line 117 isconnected to vessel 110 for removal of unreacted olefins, and otherreaction gases. Additional components or process steps may beincorporated between vessel 110 and HSD 140, or ahead of pump 105 or HSD140, if desired. High shear devices (HSD) such as a high shear, or highshear mill, are generally divided into classes based upon their abilityto mix fluids. Mixing is the process of reducing the size ofinhomogeneous species or particles within the fluid. One metric for thedegree or thoroughness of mixing is the energy density per unit volumethat the mixing device generates to disrupt the fluid particles. Theclasses are distinguished based on delivered energy density. There arethree classes of industrial mixers having sufficient energy density toconsistently produce mixtures or emulsions with particle or bubble sizesin the range of 0 to 50 microns. High shear mechanical devices includehomogenizers as well as colloid mills.

High shear devices (HSD) such as a high shear, or high shear mill, aregenerally divided into classes based upon their ability to mix fluids.Mixing is the process of reducing the size of inhomogeneous species orparticles within the fluid. One metric for the degree or thoroughness ofmixing is the energy density per unit volume that the mixing devicegenerates to disrupt the fluid particles. The classes are distinguishedbased on delivered energy density. There are three classes of industrialmixers having sufficient energy density to consistently produce mixturesor emulsions with particle or bubble sizes in the range of 0 to 50 μm.

Homogenization valve systems are typically classified as high energydevices. Fluid to be processed is pumped under very high pressurethrough a narrow-gap valve into a lower pressure environment. Thepressure gradients across the valve and the resulting turbulence andcavitations act to break-up any particles in the fluid. These valvesystems are most commonly used in milk homogenization and can yieldaverage particle size range from about 0.01 μm to about 1 μm. At theother end of the spectrum are high shear systems classified as lowenergy devices. These systems usually have paddles or fluid rotors thatturn at high speed in a reservoir of fluid to be processed, which inmany of the more common applications is a food product. These systemsare usually used when average particle, or bubble, sizes of greater than20 microns are acceptable in the processed fluid.

Between low energy-high shears and homogenization valve systems, interms of the mixing energy density delivered to the fluid, are colloidmills, which are classified as intermediate energy devices. The typicalcolloid mill configuration includes a conical or disk rotor that isseparated from a complementary, liquid-cooled stator by aclosely-controlled rotor-stator gap, which is maybe between 0.025 mm and10.0 mm. Rotors are usually driven by an electric motor through a directdrive or belt mechanism. Many colloid mills, with proper adjustment, canachieve average particle, or bubble, sizes of about 0.01 μm to about 25μm in the processed fluid. These capabilities render colloid millsappropriate for a variety of applications including colloid andoil/water-based emulsion processing such as that required for cosmetics,mayonnaise, silicone/silver amalgam formation, or roofing-tar mixing.

An approximation of energy input into the fluid (kW/L/min) can be madeby measuring the motor energy (kW) and fluid output (L/min). Inembodiments, the energy expenditure of a high shear device is greaterthan 1000 W/m³. In embodiments, the energy expenditure is in the rangeof from about 3000 W/m³ to about 7500 W/m³. The shear rate generated ina high shear device may be greater than 20,000 s⁻¹. In embodiments, theshear rate generated is in the range of from 20,000 s⁻¹ to 100,000 s⁻¹.

Tip speed is the velocity (m/sec) associated with the end of one or morerevolving elements that is transmitting energy to the reactants. Tipspeed, for a rotating element, is the circumferential distance traveledby the tip of the rotor per unit of time, and is generally defined bythe equation V (m/sec)=π·D·n, where V is the tip speed, D is thediameter of the rotor, in meters, and n is the rotational speed of therotor, in revolutions per second. Tip speed is thus a function of therotor diameter and the rotation rate. Also, tip speed may be calculatedby multiplying the circumferential distance transcribed by the rotortip, 2πR, where R is the radius of the rotor (meters, for example) timesthe frequency of revolution (for example revolutions (meters, forexample) times the frequency of revolution (for example revolutions perminute, rpm).

For colloid mills, typical tip speeds are in excess of 23 m/sec (4500ft/min) and can exceed 40 m/sec (7900 ft/min). For the purpose of thepresent disclosure the term ‘high shear’ refers to mechanicalrotor-stator devices, such as mills or mixers, that are capable of tipspeeds in excess of 5 m/sec (1000 ft/min) and require an externalmechanically driven power device to drive energy into the stream ofproducts to be reacted. A high shear device combines high tip speedswith a very small shear gap to produce significant friction on thematerial being processed. Accordingly, a local pressure in the range ofabout 1000 MPa (about 145,000 psi) to about 1050 MPa (152,300 psi) andelevated temperatures at the tip of the shear mixer are produced duringoperation. In certain embodiments, the local pressure is at least about1034 MPa (about 150,000 psi).

Referring now to FIG. 1, there is presented a schematic diagram of ahigh shear device 200. High shear device 200 comprises at least onerotor-stator combination. The rotor-stator combinations may also beknown as generators 220, 230, 240 or stages without limitation. The highshear device 200 comprises at least two generators, and most preferably,the high shear device comprises at least three generators.

The first generator 220 comprises rotor 222 and stator 227. The secondgenerator 230 comprises rotor 223, and stator 228; the third generatorcomprises rotor 224 and stator 229. For each generator 220, 230, 240 therotor is rotatably driven by input 250. The generators 220, 230, 240rotate about axis 260 in rotational direction 265. Stator 227 is fixablycoupled to the high shear device wall 255.

The generators include gaps between the rotor and the stator. The firstgenerator 220 comprises a first gap 225; the second generator 230comprises a second gap 235; and the third generator 240 comprises athird gap 245. The gaps 225, 235, 245 are between about 0.025 mm (0.01in) and 10.0 mm (0.4 in) wide. Alternatively, the process comprisesutilization of a high shear device 200 wherein the gaps 225, 235, 245are between about 0.5 mm (0.02 in) and about 2.5 mm (0.1 in). In certaininstances the gap is maintained at about 1.5 mm (0.06 in).Alternatively, the gaps 225, 235, 245 are different between generators220, 230, 240. In certain instances, the gap 225 for the first generator220 is greater than about the gap 235 for the second generator 230,which is greater than about the gap 245 for the third generator 240.

Additionally, the width of the gaps 225, 235, 245 may comprise a coarse,medium, fine, and super-fine characterization. Rotors 222, 223, and 224and stators 227, 228, and 229 may be toothed designs. Each generator maycomprise two or more sets of rotor-stator teeth, as known in the art.Rotors 222, 223, and 224 may comprise a number of rotor teethcircumferentially spaced about the circumference of each rotor. Stators227, 228, and 229 may comprise a number of stator teethcircumferentially spaced about the circumference of each stator. Inembodiments, the inner diameter of the rotor is about 11.8 cm. Inembodiments, the outer diameter of the stator is about 15.4 cm. Infurther embodiments, the rotor and stator may have alternate diametersin order to alter the tip speed and shear pressures. In certainembodiments, each of three stages is operated with a super-finegenerator, comprising a gap of between about 0.025 mm and about 3 mm.When a feed stream 205 including solid particles is to be sent throughhigh shear device 200, the appropriate gap width is first selected foran appropriate reduction in particle size and increase in particlesurface area. In embodiments, this is beneficial for increasing catalystsurface area by shearing and dispersing the particles.

High shear device 200 is fed a reaction mixture comprising the feedstream 205. Feed stream 205 comprises an emulsion of the dispersiblephase and the continuous phase. Emulsion refers to a liquefied mixturethat contains two distinguishable substances (or phases) that will notreadily mix and dissolve together. Most emulsions have a continuousphase (or matrix), which holds therein discontinuous droplets, bubbles,and/or particles of the other phase or substance. Emulsions may behighly viscous, such as slurries or pastes, or may be foams, with tinygas bubbles suspended in a liquid. As used herein, the term “emulsion”encompasses continuous phases comprising gas bubbles, continuous phasescomprising particles (e.g., solid catalyst), continuous phasescomprising droplets of a fluid that is substantially insoluble in thecontinuous phase, and combinations thereof.

Feed stream 205 may include a particulate solid catalyst component. Feedstream 205 is pumped through the generators 220, 230, 240, such thatproduct dispersion 210 is formed. In each generator, the rotors 222,223, 224 rotate at high speed relative to the fixed stators 227, 228,229. The rotation of the rotors pumps fluid, such as the feed stream205, between the outer surface of the rotor 222 and the inner surface ofthe stator 227 creating a localized high shear condition. The gaps 225,235, 245 generate high shear forces that process the feed stream 205.The high shear forces between the rotor and stator functions to processthe feed stream 205 to create the product dispersion 210. Each generator220, 230, 240 of the high shear device 200 has interchangeablerotor-stator combinations for producing a narrow distribution of thedesired bubble size, if feedstream 205 comprises a gas, or globule size,if feedstream 205 comprises a liquid, in the product dispersion 210.

The product dispersion 210 of gas particles, or bubbles, in a liquidcomprises an emulsion. In embodiments, the product dispersion 210 maycomprise a dispersion of a previously immiscible or insoluble gas,liquid or solid into the continuous phase. The product dispersion 210has an average gas particle, or bubble, size less than about 1.5 μm;preferably the bubbles are sub-micron in diameter. In certain instances,the average bubble size is in the range from about 1.0 μm to about 0.1μm. Alternatively, the average bubble size is less than about 400 nm(0.4 μm) and most preferably less than about 100 nm (0.1 μm).

The high shear device 200 produces a gas emulsion capable of remainingdispersed at atmospheric pressure for at least about 15 minutes. For thepurpose of this disclosure, an emulsion of gas particles, or bubbles, inthe dispersed phase in product dispersion 210 that are less than 1.5 μmin diameter may comprise a micro-foam. Not to be limited by a specifictheory, it is known in emulsion chemistry that sub-micron particles, orbubbles, dispersed in a liquid undergo movement primarily throughBrownian motion effects. The bubbles in the emulsion of productdispersion 210 created by the high shear device 200 may have greatermobility through boundary layers of solid catalyst particles, therebyfacilitating and accelerating the catalytic reaction through enhancedtransport of reactants.

The rotor is set to rotate at a speed commensurate with the diameter ofthe rotor and the desired tip speed as described hereinabove. Transportresistance is reduced by incorporation of high shear device 200 suchthat the velocity of the reaction is increased by at least about 5%.Alternatively, the high shear device 200 comprises a high shear colloidmill that serves as an accelerated rate reactor (ARR). The acceleratedrate reactor comprises a single stage dispersing chamber. Theaccelerated rate reactor comprises a multiple stage inline dispersercomprising at least 2 stages.

Selection of the high shear device 200 is dependent on throughputrequirements and desired particle or bubble size in the outletdispersion 210. In certain instances, high shear device 200 comprises aDispax Reactor® of IKA® Works, Inc. Wilmington, N.C. and APV NorthAmerica, Inc. Wilmington, Mass. Model DR 2000/4, for example, comprisesa belt drive, 4M generator, PTFE sealing ring, inlet flange 1″ sanitaryclamp, outlet flange ¾″ sanitary clamp, 2 HP power, output speed of 7900rpm, flow capacity (water) approximately 300 l/h to approximately 700l/h (depending on generator), a tip speed of from 9.4 m/s to about 41m/s (about 1850 ft/min to about 8070 ft/min). Several alternative modelsare available having various inlet/outlet connections, horsepower,nominal tip speeds, output rpm, and nominal flow rate.

Without wishing to be limited to a particular theory, it is believedthat the level or degree of high shear is sufficient to increase ratesof mass transfer and may also produce localized non-ideal conditionsthat enable reactions to occur that would not otherwise be expected tooccur based on Gibbs free energy predictions. Localized non idealconditions are believed to occur within the high shear device resultingin increased temperatures and pressures with the most significantincrease believed to be in localized pressures. The increase inpressures and temperatures within the high shear device areinstantaneous and localized and quickly revert back to bulk or averagesystem conditions once exiting the high shear device. In some cases, thehigh shear device induces cavitation of sufficient intensity todissociate one or more of the reactants into free radicals, which mayintensify a chemical reaction or allow a reaction to take place at lessstringent conditions than might otherwise be required. Cavitation mayalso increase rates of transport processes by producing local turbulenceand liquid micro-circulation (acoustic streaming).

Vessel. Vessel or reactor 110 is any type of vessel in which amultiphase reaction can be propagated to carry out the above-describedconversion reaction(s). For instance, a continuous or semi-continuousstirred tank reactor, or one or more batch reactors may be employed inseries or in parallel. In some applications vessel 110 may be a towerreactor, and in others a tubular reactor or multi-tubular reactor. Acatalyst inlet line 115 may be connected to vessel 110 for receiving acatalyst solution or slurry during operation of the system.

Vessel 110 may include one or more of the following components: stirringsystem, heating and/or cooling capabilities, pressure measurementinstrumentation, temperature measurement instrumentation, one or moreinjection points, and level regulator (not shown), as are known in theart of reaction vessel design. For example, a stirring system mayinclude a motor driven mixer. A heating and/or cooling apparatus maycomprise, for example, a heat exchanger. Alternatively, as much of theconversion reaction may occur within HSD 140 in some embodiments, vessel110 may serve primarily as a storage vessel in some cases. Althoughgenerally less desired, in some applications vessel 110 may be omitted,particularly if multiple high shears/reactors are employed in series, asfurther described below.

Heat Transfer Devices. In addition to the above-mentionedheating/cooling capabilities of vessel 110, other external or internalheat transfer devices for heating or cooling a process stream are alsocontemplated in variations of the embodiments illustrated in FIG. 1.Some suitable locations for one or more such heat transfer devices arebetween pump 105 and HSD 140, between HSD 140 and vessel 110, andbetween vessel 110 and pump 105 when system 1 is operated in multi-passmode. Some non-limiting examples of such heat transfer devices areshell, tube, plate, and coil heat exchangers, as are known in the art.

Pumps. Pump 105 is configured for either continuous or semi-continuousoperation, and may be any suitable pumping device that is capable ofproviding greater than 2 atm pressure, preferably greater than 3 atmpressure, to allow controlled flow through HSD 140 and system 1. Forexample, a Roper Type 1 gear pump, Roper Pump Company (Commerce Ga.)Dayton Pressure Booster Pump Model 2P372E, Dayton Electric Co (Niles,Ill.) is one suitable pump. Preferably, all contact parts of the pumpcomprise stainless steel. In some embodiments of the system, pump 105 iscapable of pressures greater than about 20 atm. In addition to pump 105,one or more additional, high pressure pump (not shown) may be includedin the system illustrated in FIG. 1. For example, a booster pump, whichmay be similar to pump 105, may be included between HSD 140 and vessel110 for boosting the pressure into vessel 110. As another example, asupplemental feed pump, which may be similar to pump 105, may beincluded for introducing additional reactants or catalyst into vessel110.

Hydration of Olefins. In operation for the catalytic hydration ofolefins, respectively, a dispersible olefin gas stream is introducedinto system 100 via line 122, and combined in line 113 with a waterstream to form a gas-liquid stream. Alternatively, the olefin gas may befed directly into HSD 140, instead of being combined with the liquidreactant (i.e., water) in line 113. Pump 105 is operated to pump theliquid reactant (water) through line 121, and to build pressure and feedHSD 140, providing a controlled flow throughout high shear (HSD) 140 andhigh shear system 100.

In a preferred embodiment, olefin gas may continuously be fed into thewater stream 112 to form high shear feed stream 113 (e.g. a gas-liquidstream). In high shear device 140, water and the olefin vapor are highlydispersed such that nanobubbles and/or microbubbles of olefin are formedfor superior dissolution of olefin vapor into solution. Once dispersed,the dispersion may exit high shear device 140 at high shear outlet line118. Stream 118 may optionally enter fluidized or fixed bed 142 in lieuof a slurry catalyst process. However, in a slurry catalyst embodiment,high shear outlet stream 118 may directly enter hydration reactor 110for hydration. The reaction stream may be maintained at the specifiedreaction temperature, using cooling coils in the reactor 110 to maintainreaction temperature. Hydration products (e.g. alcohols) may bewithdrawn at product stream 116.

In an exemplary embodiment, the high shear device comprises a commercialdisperser such as IKA® model DR 2000/4, a high shear, three stagedispersing device configured with three rotors in combination withstators, aligned in series. The disperser is used to create thedispersion of olefins in the liquid medium comprising water (i.e., “thereactants”). The rotor/stator sets may be configured as illustrated inFIG. 2, for example. The combined reactants enter the high shear devicevia line 113 and enter a first stage rotor/stator combination havingcircumferentially spaced first stage shear openings. The coarsedispersion exiting the first stage enters the second rotor/stator stage,which has second stage shear openings. The reduced bubble-sizedispersion emerging from the second stage enters the third stagerotor/stator combination having third stage shear openings. Thedispersion exits the high shear device via line 118. In someembodiments, the shear rate increases stepwise longitudinally along thedirection of the flow. For example, in some embodiments, the shear ratein the first rotor/stator stage is greater than the shear rate insubsequent stage(s). In other embodiments, the shear rate issubstantially constant along the direction of the flow, with the stageor stages being the same. If the high shear device includes a PTFE seal,for example, the seal may be cooled using any suitable technique that isknown in the art. For example, the reactant stream flowing in line 113may be used to cool the seal and in so doing be preheated as desiredprior to entering the high shear device.

The rotor of HSD 140 is set to rotate at a speed commensurate with thediameter of the rotor and the desired tip speed. As described above, thehigh shear device (e.g., colloid mill) has either a fixed clearancebetween the stator and rotor or has adjustable clearance. HSD 140 servesto intimately mix the olefin vapor and the reactant liquid (i.e.,water). In some embodiments of the process, the transport resistance ofthe reactants is reduced by operation of the high shear device such thatthe velocity of the reaction (i.e. reaction rate) is increased bygreater than a factor of about 5. In some embodiments, the velocity ofthe reaction is increased by at least a factor of 10. In someembodiments, the velocity is increased by a factor in the range of about10 to about 100 fold. In some embodiments, HSD 140 delivers at least 300L/h with a power consumption of 1.5 kW at a nominal tip speed of atleast 4500 ft/min, and which may exceed 7900 ft/min (140 m/sec).Although measurement of instantaneous temperature and pressure at thetip of a rotating shear unit or revolving element in HSD 140 isdifficult, it is estimated that the localized temperature seen by theintimately mixed reactants may be in excess of 500° C. and at pressuresin excess of 500 kg/cm² under high shear conditions. The high shearresults in dispersion of the olefin gas in micron or submicron-sizedbubbles. In some embodiments, the resultant dispersion has an averagebubble size less than about 1.5 μm. Accordingly, the dispersion exitingHSD 140 via line 118 comprises micron and/or submicron-sized gasbubbles. In some embodiments, the mean bubble size is in the range ofabout 0.4 μm to about 1.5 μm. In some embodiments, the mean bubble sizeis less than about 400 nm, and may be about 100 nm in some cases. Inmany embodiments, the microbubble dispersion is able to remain dispersedat atmospheric pressure for at least 15 minutes.

Once dispersed, the resulting olefin/water dispersion exits HSD 140 vialine 118 and feeds into vessel 110, as illustrated in FIG. 1. As aresult of the intimate mixing of the reactants prior to entering vessel110, a significant portion of the chemical reaction may take place inHSD 140, with or without the presence of a catalyst. Accordingly, insome embodiments, reactor/vessel 110 may be used primarily for heatingand separation of volatile reaction products from the alcohol product.Alternatively, or additionally, vessel 110 may serve as a primaryreaction vessel where most of the alcohol product is produced.Vessel/reactor 110 may be operated in either continuous orsemi-continuous flow mode, or it may be operated in batch mode. Thecontents of vessel 110 may be maintained at a specified reactiontemperature using heating and/or cooling capabilities (e.g., coolingcoils) and temperature measurement instrumentation. Pressure in thevessel may be monitored using suitable pressure measurementinstrumentation, and the level of reactants in the vessel may becontrolled using a level regulator (not shown), employing techniquesthat are known to those of skill in the art. The contents are stirredcontinuously or semi-continuously.

Commonly known hydration reaction conditions may suitably be employed asthe conditions of the production of an alcohol by hydrating olefins byusing catalysts. There is no particular restriction as to the reactionconditions. The hydration reaction of an olefin is an equilibriumreaction to the reverse reaction, that is, the dehydration reaction ofan alcohol, and a low temperature and a high pressure are ordinarilyadvantageous for the formation of an alcohol. However, preferredconditions greatly differ according to the particular starting olefin.From the viewpoint of the rate of reaction, a higher temperature ispreferred. Accordingly, it is difficult to simply define the reactionconditions. However, in embodiments, a reaction temperature may rangefrom about 50° C. to about 350° C., preferably from about 100° C. toabout 300° C. Furthermore, the reaction pressure may range from about 1to 300 atmospheres, alternatively 1 to 250 atmospheres.

The process according can be carried out under substantially the sameconditions as those employed in the hitherto known direct hydrationprocesses; however, in the process according to the invention it is bothpossible and advantageous for the molar ratio of water to olefin in thecharge to be very low. A molar ratio of water to olefin considerablyhigher than would correspond to the ratio in the charge may, however,occur in the reactor, since only a portion of the liquid water suppliedtogether with the charge is converted in the sump of the reactor andwithdrawn together with the stream of vaporous product. Accordingly, aconsiderably molar excess of water (or of an aqueous acid solution) maybe kept constantly available in the sump of the reactor in the processof the invention, a high selectivity of the hydration reaction foralcohol being thus ensured. It is generally sufficient for the charge tothe reactor to contain about from 1 to 1.5 moles of liquid water permole of converted olefin. Nevertheless, a molar ratio of water to olefinof from 15 to 30 or higher depending upon the required selectivity ofthe hydration process for the formation of alcohol may be adjustedwithout having to make allowance for the disadvantages involved in anelaborate recovery of the crude product from the aqueous phase.

The olefins for the reaction may be used alone or in combination as amixture of different types. The olefins can have any structure, such as,aliphatic, aromatic, heteroaromatic, aliphatic-aromatic oraliphatic-heteroaromatic. They can also contain other functional groups,and it should be determined beforehand whether these functional groupsshould remain unchanged or should be hydrated themselves.

Embodiments of the disclosed process may be suitable for hydratingstraight or branched olefins. The described process may be used forhydrating a wide variety of straight or branched chain olefinscontaining from 2 to 8 carbon atoms.

Catalyst. If a catalyst is used to promote the hydration reaction, itmay be introduced into the vessel via line 115, as an aqueous ornonaqueous slurry or stream. Alternatively, or additionally, catalystmay be added elsewhere in the system 100. For example, catalyst slurrymay be injected into line 121. In some embodiments, line 121 may containa flowing water stream and/or olefin recycle stream from vessel 110.

In embodiments, any catalyst suitable for catalyzing a hydrationreaction may be employed. An inert gas such as nitrogen may be used tofill reactor 110 and purge it of any air and/or oxygen. According to oneembodiment, the catalyst is phosphoric acid disposed on a solid supportsuch as without limitation, silica. In other embodiments, the catalystmay be sulfuric acid or sulfonic acid. Furthermore, the catalyst maycomprise a zeolite. Examples of the zeolites usable in variousembodiments include crystalline aluminosilicates such as mordenite,erionite, ferrierite and ZSM zeolites developed by Mobil Oil Corp.;aluminometallosilicates containing foreign elements such as boron, iron,gallium, titanium, copper, silver, etc.; and metallosilicatessubstantially free of aluminum, such as gallosilicates andborosilicates. As regards the cationic species which are exchangeable inthe zeolites, the proton-exchanged type (H-type) zeolites are usuallyused, but it is also possible to use the zeolites which have beenion-exchanged with at least one cationic species, for example, analkaline earth element such as Mg, Ca and Sr, a rare earth element suchas La and Ce, a VIII-group element such as Fe, Co, Ni, Ru, Pd and Pt, orother element such as Ti, Zr, Hf, Cr, Mo, W and Th. Catalyst may be fedinto reactor 110 through catalyst feed stream 115. Alternatively,catalyst may be present in a fixed or fluidized bed 142.

The bulk or global operating temperature of the reactants is desirablymaintained below their flash points. In some embodiments, the operatingconditions of system 100 comprise a temperature in the range of fromabout 50° C. to about 300° C. In specific embodiments, the reactiontemperature in vessel 110, in particular, is in the range of from about90° C. to about 220° C. In some embodiments, the reaction pressure invessel 110 is in the range of from about 5 atm to about 50 atm.

The dispersion may be further processed prior to entering vessel 110 (asindicated by arrow 18), if desired. In vessel 110, olefin hydrationoccurs via catalytic hydration. The contents of the vessel are stirredcontinuously or semi-continuously, the temperature of the reactants iscontrolled (e.g., using a heat exchanger), and the fluid level insidevessel 110 is regulated using standard techniques. Olefin hydration mayoccur either continuously, semi-continuously or batch wise, as desiredfor a particular application. Any reaction gas that is produced exitsreactor 110 via gas line 117. This gas stream may comprise unreactedolefins, for example. The reaction gas removed via line 117 may befurther treated, and the components may be recycled, as desired.

The reaction product stream including unconverted olefins andcorresponding byproducts exits vessel 110 by way of line 116. Thealcohol product may be recovered and treated as known to those of skillin the art.

Multiple Pass Operation. In the embodiment shown in FIG. 1, the systemis configured for single pass operation, wherein the output from vessel110 goes directly to further processing for recovery of alcohol product.In some embodiments it may be desirable to pass the contents of vessel110, or a liquid fraction containing unreacted olefin, through HSD 140during a second pass. In this case, line 116 is connected to line 121via dotted line 120, and the recycle stream from vessel 110 is pumped bypump 105 into line 113 and thence into HSD 140. Additional olefin gasmay be injected via line 122 into line 113, or it may be added directlyinto the high shear device (not shown).

Multiple High shear Devices. In some embodiments, two or more high sheardevices like HSD 140, or configured differently, are aligned in series,and are used to further enhance the reaction. Their operation may be ineither batch or continuous mode. In some instances in which a singlepass or “once through” process is desired, the use of multiple highshear devices in series may also be advantageous. In some embodimentswhere multiple high shear devices are operated in series, vessel 110 maybe omitted. In some embodiments, multiple high shear devices 140 areoperated in parallel, and the outlet dispersions therefrom areintroduced into one or more vessel 110.

While embodiments of the invention have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.Where numerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations. Use of broader terms such as comprises, includes,having, etc. should be understood to provide support for narrower termssuch as consisting of, consisting essentially of, comprisedsubstantially of, and the like. Accordingly, the scope of protection isnot limited by the description set out above but is only limited by theclaims which follow, that scope including all equivalents of the subjectmatter of the claims. Each and every original claim is incorporated intothe specification as an embodiment of the invention. Thus, the claimsare a further description and are an addition to the preferredembodiments of the present invention. The disclosures of all patents,patent applications, and publications cited herein are herebyincorporated by reference, to the extent they provide exemplary,procedural or other details supplementary to those set forth herein.

1. A method of hydrating an olefin comprising: a) introducing an olefingas into a water stream to form a gas-liquid stream; b) flowing thegas-liquid stream through a high shear device so as to form a dispersionwith gas bubbles having a mean diameter less than about 1 micron; and c)contacting the gas-liquid stream with a catalyst in a reactor to hydratethe olefin gas and form an alcohol.
 2. The method of claim 1, whereinthe gas bubbles have an average diameter of no more than about 100 nm.3. The method of claim 1, wherein the olefin gas comprises from 2 to 8carbon atoms.
 4. The method of claim 1, wherein (b) comprises subjectingsaid gas-liquid stream to high shear mixing at a tip speed of at leastabout 23 m/sec.
 5. The method of claim 1, wherein (b) comprisessubjecting said gas-liquid stream to a shear rate of greater than about20,000 s⁻¹.
 6. The method of claim 1, wherein forming said dispersioncomprises an energy expenditure of at least about 1000 W/m³.
 7. Themethod of claim 1, further comprising introducing the dispersion to afixed bed containing a catalyst.
 8. The method of claim 1, mixing thecatalyst with the water stream to form a slurry before (a).
 9. Themethod of claim 1, wherein the catalyst comprises comprises phosphoricacid, sulfonic acid, sulfuric acid, a zeolite, or combinations thereof.10. The method of claim 1 wherein the alcohol comprises ethanol,isopropanol, butanol, propanol, or combinations thereof.